Generally, a radial tire is formed from a plurality of tire constituent members. For example, as shown in FIG. 13, a tire T comprises rubber members such as an inner liner 2, a tread 3, side walls 4, rim strips 5, etc., and tire reinforcement members such as a carcass layer 1 containing cords made of fabric and metal, a belt layer 7, etc. The reference numeral 8 in the figure denotes a bead part including a bead core 9.
Conventionally, the carcass layer 1 comprises a lengthy strip-shaped carcass material formed by using a so-called cord woven fabric woven by using cords made of synthetic fiber, which serve as a core material, as warp and coarsely driving thin wefts, which serve as coupling, every necessary intervals in a warp direction, having rubber topping the cord woven fabric in a calendar process, cutting the semi-product to a predetermined width corresponding to a width of the carcass layer in the next process, and sequentially jointing the cut materials together in a transverse direction (width direction) to the cords, the carcass material is ordinarily wound in a rolled manner to be stocked, and the carcass material is transferred to a tire building process to be cut to a necessary length for building to be used.
However, material jointed portions of the carcass material appear in a plurality of locations in addition to a jointed portion in a single location in building on the carcass layer of a tire built by using the carcass material. Besides, since the material jointed portions and the jointed portion generated in building do not appear regularly but randomly on a tire circumference, there is a fear of making the weight balance worse, and since the jointed portions appear randomly, measures therefor are difficult. Also, due to the presence of the plurality of jointed portions, irregularities appear on tire side portions to cause a fear of degrading the external appearance and quality thereof.
Further, the conventional method requires a wide area for stock of a carcass material and also requires personnel for conveyance of the carcass material or the like, so that it is problematic in productivity and disadvantageous for building of multi-kind small-lot production.
Therefore, in recent years, instead of using a carcass material composed of a cord woven fabric, it has been proposed to align and stick a single cord as adhesive-treated or rubberized zigzaggedly in sequentially shifted positions on a core having a similar shape to a shape of an inner peripheral surface of a product tire (for example, the following Patent Document 1 or 2).
However, the proposal involves a problem that a complex large-scale apparatus is needed for sticking of the cords and when the cords remain in a state of folded back at both side ends to be made continuous, there is caused a problem that the folded portions become bulky to damage the weight balance of a tire and the quantity of cord consumed is increased, or the like. On the contrary, in the case where after the cords are stuck, both side ends thereof are cut to a width dimension corresponding to a tire, the cut process is separately needed in tire building to cause a problem in productivity.
Further, it has been proposed as a further method to align a plurality of cords to top the same with rubber to form a strip-shaped carcass material having a relatively small width and to cut the carcass material to a predetermined length to align the cut pieces with cords directed in a transverse direction (width direction) to bond the same every interval in a tire circumferential direction to constitute a carcass layer (Patent Document 3).
However, the proposal involves a problem that since a multiplicity of jointed portions every cut material piece are present every interval in the tire circumferential direction, the weight balance of a tire is made worse and a multiplicity of irregularities are generated on tire side portions. Further, it is necessary to calculate and regulate the width of the strip-shaped carcass material according to a tire size, thus causing a problem in productivity.    Patent Document 1: JP-A-4-122626    Patent Document 2: JP-A-10-151910    Patent Document 3: JP-A-2004-175157